Pitiporn Nilaphat’s research while affiliated with Phuket Marine Biological Center and other places

The bobtail squid, Euprymna hyllebergi, was cultured in the laboratory through three generations. Eggs were deposited as single egg capsules, pyramid shape with a calcified chorion. The incubation period was 14.0±1.8 days at 28°C. Hatchlings were temporarily planktonic becoming benthic after 6–8 hrs. Mean mantle length was 2.20±0.04 mm and weight 0.0041±0.0006 g. The squids were fed on larvae and postlarvae of penaeid shrimps, mysids and gobiid fish during the first month after hatching. After one month, squids were trained to accept pieces of fish meat. The squids were solitary in habit and cannibalism was observed in culture tanks. Mating and spawning was observed after 93.9±12.8 days of age. Spawning was more terminal to the life span compared to other cultured sepioid cuttlefish. Average total numbers of eggs per female was 191.3±107.4 capsules. At the age of 100 days, mean mantle length was 22.4±0.6 mm and body weight 5.88±0.17 g. Instantaneous growth rate from hatching to 100 days of age was 2.41±0.46 % by mantle length and 7.51±1.75 % by weight. Growth was similar among the three generations. Life span was average 98.9±13.6 days due to death of both sexes after the last spawning.

A cephalopod culture system is simplified in order to reduce the cost of production. An open water supply system is considered to be less laborious. The size, shape and colour of concrete tanks in the hatchery are designed from experience to suit cephalopod habits as well as other purposes. The culture protocol consists of four phases, egg and spawner collection, egg incubation, nursing and grow-out. The management techniques of large-scale aquaculture have been employed. Fourteen species of neritic cephalopods are maintained, reared and cultured in the system: three loliginids, six sepioids and five octopods, serving research activity and seed (hatchling) release for restocking programs. Four species are cultured through the complete life cycle and yield consecutive generations. About 2.1 millionseeds were annually released for restocking during the years 1990–2002. The conceptual system design for the commercial scale is proposed as five components. The components are the cephalopod hatchery, the live feed hatchery, the artificial feed plant, the grow-out facilities and the artificial spawning reef.

The bobtail squid, Euprymna hyllebergi Nateewathana, 1997 was first described from the Andaman Sea of Thailand. Recently, the species was sampled in the Gulf of Thailand. Previously, 3 species of Euprymna have been identified from the Gulf of Thailand: E. morsei (Verrill, 1881), E. stenodactyla (Grany, 1833) and E. berryi (Sasaki, 1929) but these identifications remain unresolved since the material cannot be traced.

Behavioural preference for different texture and levels of brightness of substrata was studied in cultured, juvenile sepiid cuttlefish, Sepia pharaonis and Sepiella inermis. Sand, mu,ddy sand and mud represented types of benthic sub­ stratum. Both species of cuttlefish preferred sand, to mud in long term studies (24 hrs). White, grey and black plastic plates were used as substrata representing high, medium and low levels of brightness. The cuttlefish preferred medium level of brightness during the early phase (up to 3 hrs) of the experiment. The degree of preference for substratum was higher in Sepia, living in the open sea, compared to the estuarine Sepiella. Cuttlefish selected substrata in relation to ben­ efits, which we suggest are facilitated respira­ tion, crypsis, and energy conservation. Cultured bigfin squid, Sepioteuthis lessoniana, was stud­ ied as an outgroup on preference for brightness of substrata. The bigfin squid preferred medium level of brightness during the first 6 hrs and then gradually changed to prefer low level of bright­ ness at night. We suggest that preference for brightness is associated with visual discrimina­ tion of depth in the pelagic squid performing in­ nate diurnal migration to greater depth. The present results should be applied to painting cephalopod culture tanks in order to reduce stress, promote growth and enhance the contrast of feed.

The pharaoh cuttlefish, Sepia pharaonis, were cultured in laboratory. Eggs were deposited as single eggs, round in shape and white in colour. The incubation period was 14.3 days at 28°C. Hatchlings were benthic. Mean mantle length was 0.77 cm and body weight 0.18 g. Hatchlings fed on mysids and postlarvae of penaeid shrimp. The pharaoh cuttlefish were sexually mature after 90 days and mating was observed since then. Daily growth rate was 1.37 % in mantle length and 3.40 % in body weight. Spawning occurred at the age of 110 days and one female laid from 50 to 3000 eggs. The average life span was 149.4 days due to mortality of both sex after spawning. Largest final size was 16.20 cm mantle length and 368.48 g body weight. Maximum life span was 271 days. Early maturity at a small size in culture condition revealed the alternative life strategy as short generation mode.

Behavioral study on preference on different level of brightness of substratum was held for three species of cephalopods : big fin squid, 𝑆𝑒𝑝𝑖𝑜𝑡𝑒𝑢𝑡ℎ𝑖𝑠 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 Lesson, pharaoh cuttlefish, 𝑆𝑒𝑝𝑖𝑎 𝑝ℎ𝑎𝑟𝑎𝑜𝑛𝑖𝑠 and spineless cuttlefish, 𝑆𝑒𝑝𝑖𝑒𝑙𝑙𝑎 𝑖𝑛𝑒𝑟𝑚𝑖𝑠. Plastic plates of white, grey and black in colour were used as artificial substratum presenting the high, medium and low level of brightness respectively. The big fin squid preferred medium level of brightness in first 6 hrs with high significance (p<0.01). After that, they gradual changed to prefer low brightness since nighttime and completely changed after 24 hrs (p<0.01). The pharaoh cuttlefish preferred medium level of brightness consistently with high significance (p<0.01) after 24 hrs and without significance (P>0.05) in most of other period. There was not significant difference (p>0.05) in preference of spineless cuttlefish, although medium brightness was preferred. The result was the guideline for contrast enhancing of artificial feed as well as visual stress reducing in culture tank.

Live postlarvae of banana shrimp, 𝑃𝑒𝑛𝑎𝑒𝑢𝑠 𝑚𝑒𝑟𝑔𝑢𝑖𝑒𝑛𝑠𝑖𝑠, were fed to big fin squid, 𝑆𝑒𝑝𝑖𝑜𝑡𝑒𝑢𝑡ℎ𝑖𝑠 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎, pharaoh cuttlefish, 𝑆𝑒𝑝𝑖𝑎 𝑝ℎ𝑎𝑟𝑎𝑜𝑛𝑖𝑠, and spineless cuttlefish, 𝑆𝑒𝑝𝑖𝑒𝑙𝑙𝑎 𝑖𝑛𝑒𝑟𝑚𝑖𝑠, from hatching to ten days of age or hatchling to juvenile. Size of shrimp larvae was managed to suite the size of cephalopods of each specie, preferably postlarva 5, 10 and 1 respectively. Feed conversion efficiency of spineless cuttlefish was highest (60.61%) and of big fin squid and pharaoh cuttlefish was nearly equal at 52.10% and 48.22%. The efficiency was with average feeding rate of 19.80% 27.91% and 28.17% respectively independent of stocking density. Survival of spineless and pharaoh cuttlefish was average 99.92% and 93.80% and survival of big fin squid was lower at 78.26%. Unit cost of production of big fin squid, pharaoh and spineless cuttlefish was 9.97, 19.52 and 3.54 US dollar for 100 individuals with 82.32%, 84.71% and 74.26% for cost of live feed respectively.